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3-D View of Stephan’s Quintet

October 27, 2011 Leave a comment

Subaru Telescope has added another dimension of information about one of the most studied of all compact galaxy groups—Stephan’s Quintet. Located within the borders of the constellation Pegasus, Stephan’s Quintet consists of a visual grouping of five galaxies, four of which form an actual compact group of galaxies; one additional galaxy appears in images of the group but is much closer than the others. Refinements in observations of the quintet are revealing more about its members. A comparison of images (the left and right images in Figure 1) compiled by using a suite of specialized filters with Subaru’s Prime Focus Camera (Suprime-Cam) have shown different types of star-formation activity between the closer galaxy NGC7320 and the more distant galaxies in Stephan’s Quintet. They show the quintet in 3-D.

These new images are the product of Suprime-Cam’s ability to capture images of objects in a wide field of view and to use specialized filters to focus observations according to particular research objectives. To learn about the star-forming regions in Stephan’s Quintet and their structures, observers used special narrowband filters for Hα emissions, which let in a very specific wavelength of light to indicate distinctive hydrogen emissions during active star formation. They used two Hα filters, each with a different recession velocity, i.e. the speed at which the object is moving away from the observer. They used one Hα filter with a recession velocity of 0, which means that the speed at which the object is moving away from the observer is 0 and that it is not far distant. They used another Hα filter with a greater recession velocity of 4200 miles (6,700 km) per second, an indicator of distant objects. In addition to the red color attributed to the Hα emission, blue and green colors assigned to the images from the blue and red filters captured light so that the composite tricolor images aligned with human color perception in red, green, and blue.

Full Story: http://www.naoj.org/Pressrelease/2011/08/18/index.html

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